The third war mithridatic is held 74 av. J. - C. with 63 av. J. - C. between Rome and the Pontus. It concluded by the victory from Rome, whose Royame of the Bridge, joint to the Bithynie, becomes a Roman Province, and by the suicide from Mithridate.

Mithridate counts on the assistance of king d' Arménie, Tigrane, and on that of the marianist Sertorius who, in Spain, always resists. In spring of 74 av. J. - C, it invades the Bithynie, locks up in Chalcédoine the Consul Cotta and besieges Cyzique. The other consul, Lucius Licinius Lucullus, blocks and starves besieging them, constraining Mithridate with raising the seat next spring, after very heavy losses. Destroyed Lucullus what remains pontic fleet close to Ténédos and continues Mithridate in its kingdom, where it besieges the cities of the coast. Folded up with Cabeira, Mithridate organizes the defense of the interior valleys. At the beginning of 72 before J. - C, Lucullus goes on Cabeira, but is held in failure by the unfavourable Cavalerie. It must spend the winter 72 - 71 av. J. - C on the heights dominating the city. In spring, the advertisement of a reverse throws panic in the royal army: despaired, Mithridate is withdrawn near his/her Tigrane son-in-law, king of Arménie, while the Romans seize the cities of the pontic coast.

Kept away lasting more than one year, Mithridate takes again service at the sides of Tigrane, that Lucullus had driven out its capital Tigranocerte: after having reorganized the Armenian army during the winter 69 - 68 before J. - C, it supports the summer following the attack directed by Lucullus against the town of Artaxata. Mithridate then receives from Tigrane the means necessary to recover the Petite Arménie where it is accommodated as a liberator, gaining great victories on Fabius Hadrianus and Triarius. He hopes to reconquer the pontic provinces starting from his mountain tiny room while benefitting from the lassitude of the Romans.

But, in spring of 66 before J. - C, Pumped, victorious of the Pirate S, arrives of Cilicie. After unfruitful negotiations, the Romans take the offensive and, without delivering great battle, Pompée disperses an undisciplined adversary. Mithridate gains the Colchide and spends there the winter 66 - 65 before J. - C.. Being returned Master of the the Crimea, where it crushes a revolt of his son Macharès, it on the spot recruits an army which it wants to transport in the Danubian area that the brother of Lucullus, Marcus, has just subjected. But, by a naval Blockade, Pompée pushes with the revolt the cities of the Crimea, exasperated by the Fiscalité and ruins it of their Commerce. A palace revolution, carried out by his/her son Pharnace, constrained Mithridate with the suicide. Joined to the Bithynie, its hereditary kingdom constitutes a news province, while Pharnace receives Pumped the Crimea.

Mithridate left, like Hannibal, the memory of a given adversary of Rome. But it exhausted its resources in badly calculated adventures, so that it cannot resist the final attack.